Mobile devices (also known as handheld devices) including smart phones and tablet computers have been gaining increasing performance capability over recent years. For example, the central processing units (CPUs) and graphics processing unit (GPUs) in smart phones nowadays have much more advanced computing ability than a conventional feature phone. The computing abilities of the modern smart phones enable the smart phones to perform advanced applications beyond conventional functions such as phone calling, text messaging and emailing. A modern smart phone can serve to combine the functions of portable media players, compact digital cameras, pocket video cameras, GPS navigation units, and video game consoles.
There are mobile device accessories designed to add functionalities or enhance existing functionalities for mobile devices. These mobile device accessories have interfaces to be connected with the mobile devices. The accessories can draw electrical power via the interface from the built-in batteries of the mobile devices to perform the functionalities of the accessories. The functionalities include abilities to detect and upload information to the mobile device, as well as abilities to download and present information from the mobile device.
For example, there exists a credit card reader accessory for smart phones. The credit card reader accessory can attach to and connect itself to a smart phone via a connector interface. Powered by the battery from the smart phone, the credit card reader accessory can read the information stored on the magnetic stripe of a credit card, and upload the credit card information to the smart phone. The smart phone receives the credit card information, optionally receives a customer signature via its touch screen, and then transmits the transaction information to a remote server via a network such as a cellular network.
However, these mobile device accessories pose an extra burden on the mobile devices' internal battery. While the power hungry CPUs and GPUs of modern mobile devices already cause unsatisfying total running time of the mobile devices, the power drawn from the internal battery to run the accessories further reduces the time that the mobile devices can run on a single charge of the internal batteries.
For example, there exists a projector accessory for smart phones. The projector accessory connects to a mobile device via a connector interface of the mobile device. Utilizing its CPU and/or GPU, the mobile device generates video signals and transfers the video signals to the projector accessory via the connector interface. The projector accessory receives the video signals and projects the corresponding image and/or video onto a projection screen or wall using an optical lens system. A large amount of energy is needed for the lamp of the projector accessory to emit light. The projector can include a built-in rechargeable battery so that the lamp draws power from the built-in rechargeable battery, instead of the internal battery of the mobile device. However, such a projector accessory with a built-in rechargeable battery is heavy and expensive. In addition, the built-in rechargeable battery can only serve the power need of the projector accessory but not other accessories. Once the projector accessory is detached from the mobile device, the built-in rechargeable battery within the projector accessory is no longer electrically coupled to the mobile device or other accessories.
In addition, mobile devices of various models and generations have different shapes and different types of connector interface. Generations of mobile devices continue evolving to provide more features and greater functionalities. For example, to accommodate touch screens having larger sizes and greater resolutions, the smart phones of a newer generation are typically taller and wider than the smart phones of an older generation. Also, mobile devices use different types of connector interfaces. Even a mobile device of a newer generation can have a different connector interface than the mobile device of an older generation, for reasons such as enabling faster data transfer rates and accommodating a new shape of the device. Therefore, an accessory designed for a mobile device of a particular model and generation does not generally work with other mobile devices of different models or generations.
Most form-fitting mobile device accessories are designed for a mobile device of a particular model and a particular generation. The shape of a mobile device accessory is designed to fit a particular mobile device. The mobile device accessory securely attaches to the mobile device to retain the mobility of the device so that a user can utilize the combination of the mobile device and accessory like a single device. The accessory also has an interface specifically designed to connect to a particular connector interface of the mobile device. Thus, once a mobile device changes its shape design or connector interface type in its new generation, a mobile device accessory designed for an older generation no longer can securely attach to the new generation device, or the mobile device accessory's interface can not properly connect to the newly designed connector interface of the new generation device.